Hello everyone,

A few months ago we updated our exchange 2010 server to exchange 2013. Everything is working fine, except for one little issues for one user. He can sync his calender to his phone, but when he sync the calendar clears all the appointments (that were already there) and then reloads all of them + the new ones from the exchange server.

With the exchange 2010 server when he pushed on sync now, only the new appointments that were not synced yet were loaded into the calendar. Anyone knows what could be the cause of this problem?

Regards

What device are they using? Have you tried removing and recreating the activesync account on the device?

He has a samsung GT-I9195 (s4 mini). I have told him about 3 times to do that, but I don't think he has already done that. If that won't fix the problem, any other suggestions?

There are several things you can do:

1) IIS logs related to ActiveSync will tell you how device communicates with Exchange

2) You can turn on logging in ECP of user's mailbox, repeat the action and stop logging. You will get a report of cummunication between server and a phone

3) Mostly the problem is solved by removing partnership - remove (not wipe) device from ECP of user's mailbox and try to sync again. A full sync should occur. If it does not help, check for firmware update for the phone - sometimes email clients have issues like this.

Removing and adding the account back will usually fix most problems.  Like M suggested, a software or firmware update might need to be applied to the phone.  The downside of Android devices is that every manufacturer's implementation of the OS is slightly different.